Irreversible atomic rearrangements in elastically deformed metallic glasses

The atomistic behaviour of elastically deformed Ni50Zr50 metallic glasses obtained at different quenching rates was studied by molecular dynamics. Deformation induces the irreversible rearrangement of atomic clusters of various chemical composition. The relative amount of Ni and Zr atoms participating in irreversible rearrangements depends on the quenching rate. The rearrangements are related to the potential energy difference between initial and final cluster configurations, connected in turn with volume effects. The role of local structures was investigated by focusing the attention on icosahedral coordination. The numerical findings indicate that icosahedral clusters become involved in rearrangements only after the average strain has overcome a certain value. Therefore, at small elastic strain only small atomic clusters with spatial organization different from the icosahedral one rearrange. The different involvement in rearrangements of different local structures is tentatively related to apparent local strain.